Flooding in Iowa, March 13 to 18, 2019

Area Forecast Discussion
National Weather Service La Crosse WI
605 PM CDT Wed Mar 13 2019

.SHORT TERM...(This evening through Thursday Night)
Issued at 315 PM CDT Wed Mar 13 2019

Dense fog and river rises are the main concerns through Thursday
night.

Visibilities have improved across most of northeast IA and WI as
temperatures have now warmed into the low 40s south of I-94.
Surface observations indicate 50-55F temperatures AND DEWPOINTS
are now on the I-80 corridor across IA at 20z, and shifting
northward with the warm frontal / moisture transport surge. This
will really accelerate the snow pack melt as temperatures warm
overnight. Strong inversion and snow pack melt feeding the
boundary layer should result in dense fog formation again tonight.
SREF guidance has been consistent in low visibility signals. Will
monitor the dense fog over the next hour and may be able to
cancel it early, but confidence is medium to high another advisory
will be needed overnight.

Confidence continues on around 0.25-0.50 inches of rain overnight
mainly forced by 850 mb moisture transport convergence. There may
be a rumble of thunder with some limited elevated CAPE present.
This will enhance the runoff and obviously add to river rises.
Then the dry punch of the cyclone works north with the potential
to get into the 50s over southwest/central WI which would happen
by noon Thursday as cold advection then begins. Depending on how
the inversion strength holds with the snow pack, the dense fog may
interfere with highs in the 50s. Either way, water movement will
really increase Thursday.

The transition to snow will occur Thursday night from west to
east. Will just have to watch the deformation zone on the west
side of the system to ensure more snowfall doesnt occur. Right
now minimal accumulations /less than 1/2 inch/ occur Thursday
night in southeast MN. With below freezing temperatures forecast,
the brakes will be put on the melting and runoff.

.LONG TERM...(Friday through Wednesday)
Issued at 214 PM CDT Wed Mar 13 2019

This period will be dominated by long wave troughing over the
region with northwest flow and light or no precipitation. It
offers a great period of snow melt with roughly 20F/40F for
lows/highs through the period. Small bursts of snow melt diurnally
driven. Small snow chances exist Friday morning as the system
pulls east, but otherwise Monday night is the next small chance
of light snow/rain.
&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 605 PM CDT Wed Mar 13 2019

Wet, cloudy. foggy conditions persist through Thu as low pressure
sweeps northeast across the upper mississippi river valley.

Cigs: LIFR/IFR through the night. Minor improvement likely late Thu
morning, but probably only mvfr at best for KLSE. Don't expect to
bust out into VFR until Friday afternoon-ish, but another shortwave
trough for Fri night could return more low clouds.

WX/vsby: band of showers moving through early this evening, then a
period of drizzle. Mid level dry slot and push east of better low
level thermodynamics suggest the pcpn should shut off for the
overnight hours with fog thickening in its place. Fog should improve
by late morning Thu with yet another round of showers for later
in the afternoon.

Wind: LLWS remains a concern into mid evening. At the sfc, expect
southeast tonight, swinging to the northwest later in the day Thu as
a cold front sweeps in from the west.

&&

.HYDROLOGY...
Issued at 315 PM CDT Wed Mar 13 2019

Flood Watch through 7 AM Friday. Minor to major river flooding is
expected mainly south of Interstate 90 into this weekend. Very
little ice jamming has occurred up to this point.

Rivers are now responding to snow melt and precipitation with
biggest river rises in the far southern counties as expected
/Fayette,Clayton, Grant counties/. This will spread northward to
I-90 as temperatures overnight will warm into the 40s. This
warming will have its largest effect on runoff into the
Kickapoo/Cedar/Turkey/Upper Iowa river basins.

Would expect water issues away from rivers to start increasing as
water is released from the snow. Ponding water, water over roads,
mud/rockslides.
&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch through Friday morning for WIZ017-029-032>034-
     041>044-053>055-061.

MN...Flood Watch through Friday morning for MNZ079-086>088-094>096.

IA...Flood Watch through Friday morning for IAZ008>011-018-019-029-
     030.

&&

SHORT TERM...Baumgardt
LONG TERM...Baumgardt
AVIATION...Rieck
HYDROLOGY...Baumgardt

Hazardous Weather Outlook
National Weather Service La Crosse WI
318 PM CDT Wed Mar 13 2019

IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-
032>034-041>044-053>055-061-141200-
Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette-
Clayton-Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-
Taylor-Clark-Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau-
Adams-Vernon-Crawford-Richland-Grant-
318 PM CDT Wed Mar 13 2019

This Hazardous Weather Outlook is for portions of southeast
Minnesota, northeast Iowa, and southwest into central Wisconsin.

.DAY ONE...Tonight

A Flood Watch is in effect.

River will be on the rise overnight. Warming temepratures will
enhance the snow melt, with water issues on the increase.

In addition, a few thunderstorms are possible tonight. The main
risk with any storms will be lightning.

Areas of fog are also anticipated overnight, which could be
locally dense at times.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

A Flood Watch continues through Thursday night.

Flooding is likely to develop along a number of tributaries to
the Mississippi River through late week, and potentially through
the weekend, as runoff from snow melt and rain continues. In
particular, portions of the Upper Iowa, Root, Turkey, Black, and
Kickapoo Rivers are expected to experience flooding, and urban and
poor drainage areas will also likely see significant ponding of
water.

.SPOTTER INFORMATION STATEMENT...

Rainfall reports or reports of flooding would be appreciated.

.EMERGENCY MANAGEMENT COORDINATION...

No webinar is scheduled.